U.S. patent number 4,604,295 [Application Number 06/564,150] was granted by the patent office on 1986-08-05 for visible light absorbing peroxy-esters.
This patent grant is currently assigned to Loctite Corporation. Invention is credited to Robert W. R. Humphreys.
United States Patent |
4,604,295 |
Humphreys |
August 5, 1986 |
Visible light absorbing peroxy-esters
Abstract
Compounds represented by the formula: ##STR1## wherein R.sup.1
is alkyl, aralkyl, alkoxyalkyl, alkenyl, alkynyl, carboxyalkyl or
carboxyaryl; R.sup.2 is any group which does not cause spontaneous
decomposition of the peroxy group; and x and y are integers between
0 and 4 with x+y great than or equal to 1, are disclosed. The
inventive compounds are useful as visible and UV photoinitiators
and as thermal or chemical initiators for curing compositions of
ethylenically unsaturated monomers and prepolymers.
Inventors: |
Humphreys; Robert W. R.
(Bergenfield, NJ) |
Assignee: |
Loctite Corporation (Newington,
CT)
|
Family
ID: |
24253349 |
Appl.
No.: |
06/564,150 |
Filed: |
December 22, 1983 |
Current U.S.
Class: |
427/519; 522/60;
526/232; 522/181; 560/302 |
Current CPC
Class: |
C07C
409/38 (20130101); C07C 409/40 (20130101); C08F
4/36 (20130101); C07C 2603/18 (20170501) |
Current International
Class: |
C07C
409/40 (20060101); C07C 409/00 (20060101); C07C
409/38 (20060101); C08F 4/36 (20060101); C08F
4/00 (20060101); B05D 003/06 () |
Field of
Search: |
;204/159.23 ;260/453RZ
;427/54.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Abu-Abdoun et al, Macromolecules, 1984, 17, 282-288. .
Leffler et al, J. Am. Chem. Soc., vol. 93, No. 25, 1971, pp.
7005-7012. .
L. Thijs, et al., J. Org. Chem. 44, 4123 (1979). .
S. Gupta, et al., J. Polymer Sci., 19 103-114 (1981). .
T. Sulzberg et al., J. Org. Chem. 35, 2762-2769 (1970). .
F. Moore et al., JACS, 49 1324, 1330 (1927)..
|
Primary Examiner: Newsome; John H.
Attorney, Agent or Firm: Steinkraus; Walter J. Miller;
Eugene F.
Claims
I claim:
1. A peroxy compound having the general formula: ##STR3## where
R.sup.1 is alkyl, aralkyl, alkoxalkyl, alkenyl, alkynyl or
carboxyalkyl;
R.sup.2 is any group which does not cause spontaneous decomposition
of the peroxy group;
x and y are integers between 0 and 4 and x+y is greater than or
equal to 1.
2. A compound as in claim 1 where R.sup.2 is H, alkyl, alkoxy,
carboalkoxyl, silyl, nitro, alkenyl, alkynyl, halo, or when R.sup.1
is not carboxyalkyl, amino, alkylamino or dialkylamino.
3. A compound as in claim 1 where x equals 1 and y equals 0.
4. A compound as in claim 1 wherein x equals 1 and y equals 1.
5. A compound as in claim 3 wherein the R.sup.2 groups include at
least one nitro group.
6. A compound as in claim 3 wherein the peroxy group is located in
the 1,2, or 4 position.
7. A compound as in claim 1 wherein R.sup.1 is t-butyl.
8. A compound as in claim 1 comprising a polymeric backbone having
at least one group defined by the general formula of claim 1
attached thereto through an R.sup.1 or R.sup.2 group.
9. A compound as in claim 1 decomposable into free radicals upon
exposure to light of greater than 400 nm wavelength.
10. A compound as in claim 1 selected from the t-butyl peroxy
esters of:
(a) fluorenone-1-carboxylic acid;
(b) fluorenone-2-carboxylic acid;
(c) fluorenone-4-carboxylic acid;
(d) fluorenone-2,5-dicarboxylic acid;
(e) fluorenone-2,7-dicarboxylic acid;
(f) fluorenone-2,6-dicarboxylic acid;
(g) 7-nitrofluorenone-2-carboxylic acid;
(h) 7-methoxyfluorenone-2-carboxylic acid;
(i) 7-acetylfluorenone-2-carboxylic acid;
(j) 7-chlorofluorenone-2-carboxylic acid;
(k) 7-bromofluorenone-2-carboxylic acid;
(l) 7-cyanofluorenone-2-carboxylic acid;
(m) 7-ethylfluorenone-2-carboxylic acid;
(n) 7-butylfluorenone-2-carboxylic acid;
(o) 7-butoxycarbonylfluorenone-2-carboxylic acid;
(p) 7-propoxycarbonylfluorenone-2-carboxylic acid;
(q) N,N-dialkyl-7-aminofluorenone-2-carboxylic acid;
(r) 4,5,7-trinitrofluorenone-2-carboxylic acid;
(s) 4,5-dinitrofluorenone-2,7-dicarboxylic acid;
(t) 2,5,7-trinitrofluorenone-4-carboxylic acid; and
(u) 7-nitrofluorenone-4-carboxylic acid.
11. In a free radical curable composition, a cure catalyst
comprising a peroxy ester compound as defined by the general
formula ##STR4## wherein R.sup.1 is alkyl, aralkyl, alkoxyalkyl,
alkenyl, alkynyl or carboxyalkyl
R.sup.2 is any group which does not cause spontaneous decomposition
of the peroxy group;
x and y are integers between 0 and 4 and x plus y is greater than
or equal to 1.
12. A composition as in claim 11 where the free radical curable
composition comprises at least acrylic functional monomer or
prepolymer.
13. A composition as in claim 12 further comprising an activator of
the decomposition of said peroxy compound into free radicals.
14. A composition as in claim 11 wherein said peroxy ester
structure is linked to a polymeric backbone through an R.sup.1 or
R.sup.2 group.
15. A composition as in claim 11 wherein said peroxy compound
decomposable into free radicals upon exposure to light of greater
than 400 nm wavelength.
16. A method of preparing a visible light active photoinitiator
comprising reacting an unsubstituted or substituted fluorenone
carboxylic or dicarboxylic acid chloride with an organic
hydroperoxide.
17. A method of providing a cured coating on a substrate having
shadow areas not accessible by direct radiation, the method
comprising applying a coating of a free radical curable composition
to the substrate, the curable composition including:
(a) a peroxy initiator of the general formula ##STR5## where
R.sup.1 is alkyl, aralkyl, alkoxyalkyl, alkenyl, alkynyl or
carboxalkyl;
R.sup.2 is any group which does not cause spontaneous decomposition
of the peroxy group;
x and y are integers between 0 and 4 and x plus y is greater than
or equal to 1, and
(b) a peroxide activator,
exposing the substrate to UV or visible light to rapidly cure the
light accessible areas and curing the light inaccessible areas by
chemical activation of said peroxy initiator.
18. A method as in claim 17 wherein said light inaccessible areas
are cured at ambient temperature.
19. A method of curing a free radically polymerizable formulation
comprising an olefinically unsaturated compound and a compound of
the formula: ##STR6## wherein R.sup.1 is alkyl, aralkyl,
alkoxyalkyl, alkenyl, alkynyl, carboxyalkyl, or carboxaryl;
R.sup.2 is any group which does not cause spontaneous decomposition
of the peroxy groups;
x and y are integers between 0 and 4 and x plus y is greater than
or equal to 1,
the method comprising exposing the formulation to visible light for
sufficient time to cure the formulation.
20. A method as in claim 19 where R.sup.1 is alkyl, aralkyl,
alkoxyalkyl, alkenyl, alkynyl or carboxyalkyl.
21. A method as in claim 20 where R.sup.1 is alkyl.
22. A method as in claim 19 where R.sup.2 includes at least one
nitro group.
23. A method as in claim 21 where the unsaturated compound is an
acrylic functional compound.
24. A peroxy compound as in claim 1 wherein R.sup.1 is alkyl.
Description
BACKGROUND OF THE INVENTION
Photoinitiated curing of olefinically unsaturated compositions has
a broad spectrum of industrial uses including polymer synthesis,
elastomer vulcanization and the curing of adhesives, coatings and
films. Typically the photoinitiators in such systems have primary
activity in the ultraviolet (UV) region, with little or no visible
light sensitivity. While this is often a useful property, e.g.,
when the composition needs to be stored or preapplied under
conditions subject to visible light exposure, there are many
applications in which it is desirable that a composition be
cureable by exposure to visible light. For instance, in adhesive
applications when bonding polymers which are transparent to visible
light but not to UV light, effective visible light photoinitiators
are particularly desirable. Polycarbonates are examples of such
visible light transparent, UV light opaque polymers.
In other applications visible light initiated curable compositions
are desirable because visible light is much cheaper and safer to
produce than UV and requires less specialized equipment.
L. Thijs, S. Gupta, and D. Neckers, J. Org. Chem., 44 4123 (1979),
describe the synthesis and use of t-butyl peresters having an
associated benzophenone chromophore as photoinitiators. These
authors suggest that the photodecomposition characteristics of
these perester compounds can be altered by the absorption
characteristics of the associated chromophore. The same authors
published subsequent papers, J. Polymer Sci., 19, 103-114 and
855-868 (1981), in which the photoinitiating characteristics of
other benzophenone peresters are examined.
SUMMARY OF THE INVENTION
The present invention relates to a novel class of peroxy ester or
diacyl peroxide compounds which will efficiently generate free
radicals capable of initiating polymerization of unsaturated
olefins upon exposure to UV or visible light. The compounds are
derivatives of 9-fluorenone which include at least one peroxy ester
or diacyl peroxide group attached thereto. The compounds may be
generally represented by formula (1): ##STR2## where R.sup.1 is
alkyl, aralkyl, alkoxyalkyl, alkenyl, alkynyl, carboxyalkyl or
carboxyaryl;
R.sup.2 is any group which does not cause spontaneous decomposition
of the peroxy group; and
x and y are integers between 0 and 4 with x+y greater than or equal
to 1.
The various R.sup.1 and R.sup.2 groups many be the same or
different. Preferably R.sup.2 is selected from H, alkyl, alkoxy,
carboalkoxy, silyl, organosiloxy, nitro, alkenyl, alkynyl, halo,
or, when R.sup.1 is not carboxyalkyl or carboxyaryl, amino,
alkylamino or dialkylamino.
The inventive fluorenone peroxy esters will typically be monomeric
molecules but may also be advantageous to utilize as
polyphotoinitiators by linking the peroxy ester to a polymeric
backbone through an appropriate R.sup.1 or R.sup.2 group.
The invention also encompasses a method of curing olefinically
unsaturated compounds by exposing same to visible or UV light in
the presence of a compound of the invention. Compositions of the
inventive photoinitiators with olefinically unsaturated monomers
are also within the scope of the instant invention.
The inventive peresters and diacyl peroxides will also undergo
typical peroxide decomposition reactions, forming free radicals
under heat or chemical activation. Accordingly, the inventive
compounds may be used as a single initiator of a multiple cure
system. For instance, coating compositions may be formulated
employing the inventive compounds in which the surface is cured
rapidly by exposure to UV or visible light with shadow areas curing
by a slower chemically or heat activated mechanism.
DETAILED DESCRIPTION OF THE INVENTION
The inventive peroxy esters may be prepared from acid chlorides of
the appropriate fluorenone carboxylic acid and an R.sup.1 peroxy
compound. The fluorenone carboxylic chlorides are prepared by
conventional synthetic methods from the acid, using thionyl
chloride, phosphorus pentachloride or other conventional
reagents.
Fluorenone carboxylic acids are known. Examples include:
(a) fluorenone-1-carboxylic acid
(b) fluorenone-2-carboxylic acid
(c) fluorenone-4-carboxylic acid
(d) fluorenone-2,5-dicarboxylic acid
(e) fluorenone-2,7-dicarboxylic acid
(f) fluorenone-2,6-dicarboxylic acid
(g) 7-nitrofluorenone-2-carboxylic acid
(h) 7-methoxyfluorenone-2-carboxylic acid
(i) 7-acetylfluorenone-2-carboxylic acid
(j) 7-chlorofluorenone-2-carboxylic acid
(k) 7-bromofluorenone-2-carboxylic acid
(l) 7-cyanofluorenone-2-carboxylic acid
(m) 7-ethylfluorenone-2-carboxylic acid
(n) 7-butylfluorenone-2-carboxylic acid
(o) 7-butoxycarbonylfluorenone-2-carboxylic acid
(p) 7-propoxycarbonylfluorenone-2-carboxylic acid
(q) N,N-dialkyl-7-aminofluorenone-2-carboxylic acid
(r) 4,5,7-trinitrofluorenone-2-carboxylic acid
(s) 4,5-dinitrofluorenone-2,7-dicarboxylic acid
(t) 2,5,7-trinitrofluorenone-4-carboxylic acid.
Synthesis methods for the aforementioned fluorenone carboxylic
acids may be found in the following references, the appropriate
disclosures of which are incorporated herein by reference. Compound
a: J. Am. Chem. Soc., 57, 2174(1935). Compounds b and d-q: U.S.
Pat. No. 3,987,088. Compound c: Fieser and Fieser, "Advanced
Organic Chemistry," Rheinhold Publishing Corporation, p. 807(1961).
Compound r: U.S. Pat. Nos. 3,637,798 and 4,050,934. Compounds s and
t: U.S. Pat. No. 3,637,798. A variety of additional mono- or
poly-chloro, nitro, bromo, cyano, benzoyl and fluoro substituted
fluorenone carboxylic acids are also reported in U.S. Pat. No.
3,864,126 as precursors to corresponding fluorenone carboxylic acid
esters .
Synthesis of the inventive peroxy esters or diacyl peroxides may be
exemplified by the following Examples 1-5.
EXAMPLE 1
9-Fluorenone-4-carbonylchloride was obtained by reacting 4.48 g
9-fluorenone-4-carboxylic acid and 12 ml (19.6 g) of SOCl.sub.2 for
three hours at reflux in a flask equipped with condensor, stirring
bar and drying tube. Most of the excess SOCl.sub.2 was removed by
distillation (9 ml) and the remaining reaction product diluted with
about 20-25 ml benzene. Hexane was then added until the solution
became turbid, and the mixture refrigerated overnight. The
resulting crystalline precipitate was collected by vacuum
filtration, washed with hexane and dried in a vacuum desicator to
yield 4.1 g of deep yellow crystals.
In a 125 ml erlenmeyer flask were placed 30 ml benzene and 1.23 g
potassium t-butoxide. 1.10 g t-butyl hydroperoxide was added with
stirring, producing a thick pasty mass. After 30 min., a solution
of 2.43 g 9-fluorenone-4-carbonylchloride in 30 ml methylene
dichloride was added in two equal portions and the mixture stirred
in the dark for about an hour. The reaction mixture was then
filtered, the filtrate placed on a rotary evaporator, and the
solvents removed at temperatures of 35.degree. C. or less. The
product, containing the desired t-butyl perester of
9-fluorenone-4-carboxylic acid (4FP), was an orange oil.
EXAMPLE 2
The t-butyl peroxy ester of fluorenone-2-carboxylic acid (2FP) was
prepared from the acid by the method of Example 1. The product was
a bright yellow solid.
EXAMPLE 3
The t-butyl peroxy ester of fluorenone-1-carboxylic acid was also
prepared from the acid in the same manner as in Example 1.
EXAMPLE 4
9-Fluorenone-4-carboxylic acid (80 gms) (Aldrich Chemical Co.) and
800 ml concentrated nitric acid were placed into a two liter
3-necked flask equipped with stirrer, condenser, heater and
thermometer. The mixture was heated to 90.degree. C. for 11/2
hours. Mixture was then poured into ice water. The resulting ppt of
7-nitro-9-fluorenone-4-carboxylic acid (7-NF acid) was washed with
water, dried and recrystallized from glacial acidic acid, yielding
bright yellow crystals having a Mp: 264.degree.-266.degree. C.
(uncorrected).
To a 500 ml flask equipped with stirrer, condenser and drying tube
were added: 15.5 gm 7-NF acid; 12.8 gm PCl.sub.5 ; 100 gm toluene
and 5 ml DMF. The mixture was refluxed for 6 hrs. The hot liquid
reaction product was then decanted and cooled after which the
yellow ppt. was filtered, washed with hexane, collected and dried.
The melting point of the resulting 7-NF acid chloride was
199.degree.-201.degree. C. (uncorrected).
The desired t-butyl perester of 7-nitro-9-fluorenone-4-carboxylic
acid (7NFP) was then prepared by reaction of 10.12 gms of the 7-NF
acid chloride; 4.27 gms of triethylamine; 3.49 gms t-butyl
hydroperoxide; and 300 ml methylene dichloride. The reaction was
conducted by adding the hydroperoxide and triethyl amine in 50 mls
of the methylene dichloride dropwise with stirring to a one liter
flask in an ice bath containing the remaining ingredients over 15
min. The mixture was stirred for 4 hours. 200 ml ether was then
added and the ppt. filtered and discarded. The solvent was removed
from the remaining solution to yield 7-NFP as a yellow solid having
a MP of about 170.degree.-175.degree. C. (uncorrected) with
decomposition.
EXAMPLE 5
A diacid, 9-fluorenone-2,7-dicarboxylic acid, and the corresponding
acid chloride were prepared by the method of Sulzberg & Cotter,
J. Org. Chem., 35 2762,2767(1970). The corresponding di-t-butyl
perester (2,7-DFP) was then prepared using the procedures of
Example 4.
Compounds of the invention are advantageously utilized in
compositions with free radical curable monomers. Useful
concentrations are typically within the range 0.1-10 weight percent
based on monomer weight. Preferred ranges are between about 1 and
5%.
The inventive compounds can be used to initiate polymerization even
when irradiated through UV filtering materials.
EXAMPLE 6
A composition comprising polyethylene glycol dimethacrylate with
about 5 weight percent 4FP was prepared. A film of the material was
irradiated with a medium pressure mercury lamp (Technocure System).
The film cured within 5 seconds.
A 20 mil film of the same composition was then irradiated with the
same lamp through a 3/8" polycarbonate filter. The transmission
spectrum of the filter showed 0% transmission of light below about
390 nm. The film cured in 10 seconds. Cure was also effected
through polycarbonate headlight covers.
The inventive compounds have also been used to cure methacrylate
compositions through laminated auto glass and poly(methyl
methacrylate).
Compounds of the invention are stable for extended periods of time
in compositions of polymerizable monomers.
EXAMPLE 7
A hydroxypropyl methacrylate capped block copolymer comprising a
flexible segment of butadiene/acrylonitrile and rigid segments
obtained from toluene diisocyanate and hydrogenated bisphenol A,
(80 weight percent) was mixed with isobornyl methacrylate (18
weight percent) and 2 weight percent 4FP. A thin film of this
mixture cured completely in 30 seconds when irradiated through
polycarbonate and in 10 seconds when irradiated directly. The
mixture was stored at room temperature in an opaque plastic syringe
for about 2 months after which the material appeared to cure as
rapidly as when fresh.
EXAMPLE 8
In order to evaluate the relative efficiency of the inventive
compounds as visible and thermal initiators samples of 4FP, 2FP and
7NFP were compared to t-butyl perbenzoate (TBP) in a composition
containing 60% of a methacrylate terminated polyester-urethane
resin (PEUMA) and 40% hydroxypropyl methacrylate. The respective
initiators were added at molar levels equivalent to 0.5% TBP by
weight.
The compositions were placed on glass slides as specified in Table
I and irradiated through a polycarbonate filter. Results are given
in Table I.
TABLE I ______________________________________ VISIBLE LIGHT CURING
Initiator Glass Slide* Glass Slides 0 Gap #
______________________________________ 7NFP 20 sec - cured with 15
sec. cured tacky surface 4FP 20 sec uncured 30-35 sec. cured 40 sec
gelled 2FP 20 sec - surface cure 25 sec. cured 50 sec cured - tacky
TBP NEG NEG 100 sec Blank NEG --
______________________________________ *3 drops of formulation
placed on glass slide # 3 drops of formulation between two glass
slides Other samples of the same compositions were heat cured as
indicated in Table II.
TABLE II ______________________________________ HEAT CURING
Dark/Ambient Dark 130-140.degree. C. 130-140.degree. C. (film or 10
min (between 2 min Initiator glass slide) glass slides) (1/4" in
metal cup) ______________________________________ 7NFP No cure
Fixtured-cured Partial cure 4FP No cure Fixtured-cured Partial cure
TBP No cure Fixtured-cured Cured Blank No cure No cure No cure
______________________________________
EXAMPLE 9
The capability of the inventive compounds to initiate anaerobic
cure was demonstrated with a formulation consisting of 4.84 wt. %
4FP, 1.08% saccharin, 300 PPM NaEDTA, 120 PPM Napthoquinone, and
the balance poly(ethylene glycol) dimethacrylate. This sample was
compared to two control compositions, one containing an equivalent
amount of TBP (3.16%) in place of the 4FP and the other, a blank,
containing no initiator. The compositions were applied between 1"
sandblasted steel laps primed with Primer N.TM., an anaerobic
activator sold by Loctite Corporation. After 20 minutes the 4FP and
TBP compositions had both fixtured whereas the blank did not
fixture even after 20 minutes.
EXAMPLE 10
Compositions were prepared by intimate mixing of the ingredients
listed in Table III. Each composition was cured by placing three
drops between glass slides and irradiating through a polycarbonate
filter as in Example 8. Compositions A and C gelled in 20-25 sec.
Composition B gelled within 20 secs. and cured hard within 25
secs.
TABLE III ______________________________________ Composition
Ingredients A B C ______________________________________ PEUMA
resin 22.0 g 22.0 g 22.0 g Hydroxypropyl methacrylate 14.98 g 14.98
g 14.98 g 4FP .19 g 2,7-DFP .26 .13
______________________________________
Acrylic functional monomers and prepolymers (i.e., compounds with
acrylate, methacrylate, ethacrylate, etc. functionality) are the
preferred ethylenically unsaturated compounds in the curable
compositions of the invention. However, other free radical
polymerizable compounds may also be used in the inventive
compositions. Examples of such other compounds include
acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,
N-substituted acrylamides, vinyl propionate, vinyl succinate, vinyl
ethers, styrene, alkyl styrenes, halo styrenes, divinyl benzene,
vinyl napthalene, N-vinylpyrrolidone, vinyl chloride, vinylidene
chloride, diallyl phthalate, diallyl maleate, triallyl
isocyanurate, triallyl phosphate and ethylene glycol diallyl ether.
Prepolymers containing functional groups which will react with free
radicals to crosslink or copolymerize with the foregoing monomers
may also be compounded with the inventive photoinitiators to
produce curable compositions.
The efficiency of the inventive compounds as visible light
initiators will vary depending on the nature of the R.sup.1 and
R.sup.2 substituents which increase the wavelength of the maximum
absorbance in the UV-Vis spectrum of the acid will produce more
efficient visible light photoinitiators, provided that the molecule
continues to absorb sufficient energy to cleave the perester or
diacyl peroxide linkage. Also, since the cleavage reaction for
diacyl peroxides has a lower activation energy than for peroxy
esters, the embodiments of the invention in which R.sup.1 is acyl
will generally be more efficient visible light initiators than
those in which R.sup.1 is alkyl. An example of a diacyl peroxide of
the invention is the reaction product of fluorenone carboxylic acid
chloride and m-chloroperbenzoic acid or its sodium or potassium
salt.
* * * * *